refactor : Number Class 정적팩토리로 표현, 메모리에 저장

src/main/java/calculator/Number.java

@@ -0,0 +1,52 @@
+package calculator;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class Number {
+    private static final Pattern NUMERIC_PATTERN = Pattern.compile("[+]?\\d+");
+    private static final Map<Integer, Number> positiveNumbers = new HashMap<>();
+    private int value;
+
+    private Number() {
+        this.value = 0;
+    }
+
+    private Number(int num) {
+        this.value = num;
+    }
+
+    public static Number sumOf(List<String> strings) {
+        Number number = new Number();
+        for (String string : strings) {
+            number.add(ofPositive(string).value);
+        }
+        return number;
+    }
+
+    private static Number ofPositive(String stringNumber) {
+        int num = parsePositiveInt(stringNumber);
+        Number number = positiveNumbers.getOrDefault(num, new Number(num));
+        positiveNumbers.put(num, number);
+        return number;
+    }
+
+    private static int parsePositiveInt(String string) {
+        Matcher isNumeric = NUMERIC_PATTERN.matcher(string);
+        if (isNumeric.matches()) {
+            return Integer.parseInt(string);
+        }
+        throw new IllegalArgumentException();
+    }
+
+    public int getValue() {
+        return this.value;
+    }
+
+    private void add(int number) {
+        this.value += number;
+    }
+}

src/main/java/calculator/StringCalculator.java

@@ -3,6 +3,7 @@
 import org.apache.logging.log4j.util.Strings;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -18,8 +19,8 @@ public int calculate(String input) {
             return 0;
         }
         List<String> inputs = splitInputs(input);
-        PositiveNumber positiveNumber = new PositiveNumber(inputs);
-        return positiveNumber.getValue();
+        Number number = Number.sumOf(Collections.unmodifiableList(inputs));
+        return number.getValue();
     }
 
     private List<String> splitInputs(String input) {

src/test/java/calculator/PositiveNumberTest.java → src/test/java/calculator/NumberTest.java

@@ -6,13 +6,14 @@
 import org.junit.jupiter.params.provider.MethodSource;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Stream;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
-class PositiveNumberTest {
+class NumberTest {
     private static final Stream<Arguments> throwWithNonNumericExceptionArguments() {
         return Stream.of(
                 arguments(Arrays.asList("-1", "2", "3")),
@@ -24,6 +25,8 @@ private static final Stream<Arguments> throwWithNonNumericExceptionArguments() {
     @MethodSource("throwWithNonNumericExceptionArguments")
     @DisplayName("숫자 이외의 값 또는 음수는 RuntimeException을 발생한다.")
     void throwWithNonNumericException(List<String> inputs) {
-        assertThrows(IllegalArgumentException.class, () -> new PositiveNumber(inputs));
+        assertThrows(IllegalArgumentException.class,
+                () -> Number.sumOf(Collections.unmodifiableList(inputs))
+        );
     }
 }

src/test/java/kitchenpos/controller/MenuGroupRestControllerTest.java

@@ -2,21 +2,16 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import kitchenpos.bo.MenuGroupBo;
-import kitchenpos.model.MenuGroupTest;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
-import org.springframework.http.MediaType;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 
-import static org.mockito.BDDMockito.given;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;